1. Field of the Invention
This invention relates to an internal combustion engine. In particular the present invention provides a double action piston driven in both the up stroke and the down stroke.
2. Description of the Prior Art
Internal combustion engines using a reciprocating piston have been around for many years. The engines operate on the principle of exploding gases forcing a piston downwardly in a cylinder transferring the power to a drive mechanism. Such engines typically provide a single cycle of operation (intake, compression, power and exhaust) over four strokes of a piston. These engines provide for power on only the power stroke. The intake, compression and exhaust strokes require an input of auxiliary power to achieve the necessary function. In the original designs of engines, the auxiliary power was provided by flywheels which stored some of the energy developed by the power stroke and fed it back to the piston to accomplish the exhaust, intake and compression strokes to enable another power stroke to take place. In single cylinder engines, the size of flywheel required was enormous and reduced the potential efficiency of the engine for power output to the drive mechanism.
To provide optimum efficiency for a four stroke engine, a minimum of four cylinders is generally required. In this way one of the four cylinders is always in the power stroke, thus transferring power to the drive mechanism and providing the auxiliary power to operate the other pistons through their exhaust, intake and compression stokes. However, as only one of the four pistons is in the power stroke at any one time, the potential efficiency of the operation of the engine is reduced as some of the output power must be used to drive the other pistons. Even increasing the number of cylinders to more than four, such as six or eight does not overcome this drawback.
The two stroke engine was developed to improve efficiency. In a two stroke engine, the power and intake strokes are combined as are the exhaust and compression. In this way, the piston only requires one up stoke and one down stroke to complete the cycle, thus doubling potential efficiency. However, because of the combination of strokes required in the operation of the two stoke engine, some of this potential efficiency is lost to the decreased efficiency of the combined stroke compared to individual strokes. Other problems are heat generation, shorter operating life, need for lubricating oil to be mixed with fuel and a high level of hydrocarbons in the exhaust.
Alternative forms of internal combustion engines have been developed in attempts to overcome the inefficiencies. For example, Wankel rotary engines have been developed to overcome the need to transform the up and down stroke of the pistons to the circular motion of a drive shaft. The rotary engine uses a rotating piston having multiple faces interacting with the walls of a cylinder to provide varying volumes of chambers as the cylinder rotates to allow for the four stroke operation. While the potential efficiency of the rotary engine is greater than a reciprocating piston engine, the power stroke of the piston is still required to operate the engine through the exhaust, intake and compression strokes.
There still remains a need for a engine with increased efficiency in which the power stroke can provide all of its output to the desired operation of the engine and is not needed to operate the other cylinders through their other strokes.